The present invention relates to apparatus for inserting intraocular lenses (IOLs) into an eye. More particularly, the present invention relates to insertion apparatus having a hollow tube through which an acrylic IOL is pushed with a push rod into an eye.
The human eye is susceptible to numerous disorders and diseases, a number of which attack the crystalline lens. For example, cataracts mar vision through cloudy or opaque discoloration of the lens of the eye. Cataracts often result in partial or complete blindness. If this is the case, the crystalline lens can be removed and replaced with an intraocular lens, or IOL.
An intraocular lens (IOL) is implanted in the eye, for example, as a replacement for the natural crystalline lens after cataract surgery or to alter the optical properties of (provide vision correction to) an eye in which the natural lens remains. IOLs often include a disk-like optic, and preferably at least one flexible fixation member or haptic which extends radially outward from the optic and becomes affixed in the eye to secure the lens in position. The optic normally includes an optically clear lens. Implantation of such IOLs into the eye involves making an incision in the eye. It is advantageous, to reduce trauma and speed healing, to have an incision size as small as possible.
The optics may be constructed of rigid biocompatible materials such as polymethyl methacrylate (PMMA) or deformable materials such as silicone polymeric materials, acrylic polymeric materials, hydrogel polymeric materials, and the like. The deformable materials allow the IOL to be rolled or folded for insertion through a small incision into the eye. A substantial number of instruments have been proposed to aid in inserting such a foldable lens in the eye. In a popular apparatus, the optic begins in the shape of a taco and is pushed through an insertion cartridge, progressively rolling into a tubular shape to fit through the incision. Such an exemplary insertion system is disclosed in Makker et al., U.S. Pat. No. 5,942,277, the contents of which are expressly incorporated by reference herein.
The two primary IOL materials are silicone and acrylic. Silicone IOLs are more pliable and can be folded into smaller tubes without unduly stressing the insertion cartridge, or requiring excessive push force which can violently expel the IOL from the cartridge. However, acrylic lenses are indicated for some patients and are inserted in much the same way as silicone IOLs, although using larger bore cartridges to mitigate the problems caused by the lower flexibility of the acrylic. Because the cartridge bore is larger, the incision is also necessarily larger.
In view of the foregoing, it would be beneficial in the art to provide an IOL insertion apparatus that enables acrylic IOLs to be inserted through smaller incisions.
The present invention provides new and enhanced apparatuses for implanting acrylic IOLs into the eye. The apparatuses enable acrylic IOLs to be inserted through smaller incisions than previously was possible. In general, the invention provides an insertion apparatus wherein a cartridge having a relatively small open distal mouth receives an acrylic IOL, and a modified push rod is used to urge the IOL through the cartridge.
In accordance with the first aspect of present invention, an insertion apparatus for intraocular lenses includes an intraocular lens having an optic and at least one fixation member, an insertion cartridge, and a push rod. The insertion cartridge has a proximal loading chamber sized to receive the intraocular lens in an unfolded configuration, and a distal injection tube having an open distal mouth sized to fit through an incision in the eye. The insertion cartridge further includes a lumen connecting the loading chamber and the open distal mouth that reduces in size therebetween to cause the intraocular lens to fold into a smaller size than its unfolded configuration when pushed through the lumen. The push rod has a distal tip for pushing the intraocular lens through the insertion cartridge from the loading chamber through the connecting lumen and out the open distal mouth. The push rod defines a longitudinal axis, and wherein the distal tip in transverse cross-section has a longitudinally extending runner on its lower surface and on one side thereof that creates an adjacent relief channel on the other side.
In accordance with a preferred aspect, the distal tip has a generally trapezoidal cross-section. Further, the distal tip in cross-section may have a cross-section perpendicular to the longitudinal axis that is non-symmetric across any plane that includes the longitudinal axis. In addition, the distal face of the distal tip they have a horizontal groove therein that creates a projection in the runner. The generally trapezoidal cross-section of the distal tip may have a rounded upper end that is larger than a lower end.
Desirably, the maximum cross-sectional dimension of the distal tip is slightly less than the inner diameter of the open distal mouth of the insertion cartridge. In one embodiment, the inner diameter of the open distal mouth of the insertion cartridge is less than about 2 mm.
In accordance with another aspect of the invention, and insertion apparatus for intraocular lenses comprises an intraocular lens having an optic and at least one fixation member, an insertion cartridge, and a push rod. The insertion cartridge is as described above, and the push rod has a distal tip for pushing the intraocular lens through the insertion cartridge from the loading chamber through the connecting lumen and out the open distal mouth. The push rod defines a longitudinal axis, and the distal tip of the push rod has at least one relief channel extending generally parallel to the longitudinal axis and on a lower side thereof. The relief channel is positioned to receive the fixation member of the intraocular lens as the distal tip contacts and pushes on the optic.
The distal tip may have a generally rounded trapezoidal cross-section, and a longitudinally extending runner on its lower surface and on one side thereof that creates the relief channel on the other side. In one embodiment, the distal face of the distal tip has a horizontal groove therein that creates a projection in the runner. Two relief channels may be provided on either side of the distal tip.
In accordance with a further aspect of the invention, an insertion apparatus for acrylic intraocular lenses comprises an intraocular lens having an acrylic optic and at least one fixation member. A polymer insertion cartridge having a proximal loading chamber is sized to receive the intraocular lens in an unfolded configuration. A distal injection tube on cartridge has an open distal mouth sized to fit through an incision in the eye. The insertion cartridge further includes a lumen connecting the loading chamber and the open distal mouth that reduces in size therebetween to less than about 2.0 mm at the open distal mouth to cause the intraocular lens to fold into a smaller size than its unfolded configuration when pushed through the lumen. At least a portion of the connecting lumen may have a lubrication enhancement incorporated into the polymer and concentrated near the surfaces of the cartridge.
Each and every feature described herein, and each and every combination of two or more of such features, is included within the scope of the present invention provided that the features included in such a combination are not mutually inconsistent.
Additional aspects, features, and advantages of the present invention are set forth in the following description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numbers.